Mastitis in cows milked in an automated or conventional milking system in New Zealand

摘要

The viability of automated milking systems (AMS) for pasture-based dairying has been studied in New Zealand in the past four years. Automatic milking differs from conventional milk harvesting systems (CMS) in a number of ways, which may impact on udder health. These include fewer machines/cow, distributed vs. batch milking, variable milking intervals, automatic udder health monitoring systems, and pre and post-milking teat sanitation procedures. Three seasons of data from two pasture-based research farms that milked cows with either a two unit AMS or a 30 bail rotary CMS were compared. Quarter milk samples were collected routinely from all cows for bacteriological analysis during the 2002-03, 2003-04 and 2004-05 seasons, with sampling occurring throughout lactation and at detection of clinical mastitis (CM) cases. The number of cows in the AMS herd ranged from 94 to 196 and in the CMS herd, from 289 to 324 across the seasons. Clinical mastitis affected 7, 11, and 15 cows/100 cows/season in the AMSherd and 24, 23 and 14 cows/100 cows/season in the CMS across the three seasons, with Streptococcus uberis isolated from approximately 50% of CM cases from both herds. Prevalence of S. uberis post-calving averaged 8% of cows for the AMS and 16% for the CMS across the three seasons. We compared several indicators of udder health between an AMS and a CMS herd managed under pastoral conditions.